A33Zab

Thx for your efforts to make this visible!
need some time now to study your valuable graphs and comments.

@ Machinebird:

Thx for the Fly-By-Wire A Primer for Aviation Accident Investigators
For the A3x series the - pitch rate - is indeed a input signal.

PJ2 posted this logic of A320 in the previous thread.

A33Zab

The last I heard about this it was a testcase for Quantas only.
But some years had passed now, it could have been introduced by now.

Ian W

Reply to MM43:
An interesting quote from the document:

"It is important to know that if such a thrust increase was applied when
the aircraft is already stalled, the longitudinal effect would bring the
aircraft further into the stall, to a situation possibly unrecoverable."

An admission indeed.

A33Zab

Hi airtren:

AKA as ECAM.
LEDs are in Master Warning [RED] & Master Caution [Amber]
and comes with audible alarms & chimes.

airtren

mm43,

Thanks for the graph, it makes it easier to see.

Did you leave out the "roll commands" and "rudder commands" graphs intentionally?

They can help correlate visually the PF actions with the control surface deflections.

The "rudder" commands and control surface deflections on the graphs are confirmed by the CVR transcript's call to "attention with the rudder" by the Captain, in the same time interval with the graphs.

mm43

Ian W;
I believe that Airbus had worked out from the ACARS sequence the most likely scenario, and that statement is valid when compared with the Thrust and Pitch Attitude graphic shown on the previous page.

We now know that there was no escape as they didn't 'know' they were STALLED.

mm43

airtren;Yes I did. The rudder commands are all yaw damper commands, except in one instance where the pedal was jumped on. When looking at the Pedal trace and comparing it with the Yaw trace I noted that the algebraic sum was applied to the rudder and it recorded more than the RTLU restriction when the pedal was hard down.

airtren

Hello A33Zab

Thanks for pointing that out. Conforming to the existing color code scheme adds consistency to the a/c-human interface.

Elaborating further:

F - fatal --- most important, and highest priority -- ignoring may be fatal.
W - warning --- awareness of an abnormal condition is important, but ignoring it does not have fatal consequences
I - informational - information only, for pilot awareness.

The simplicity of a 3 LED Error Panel is a reincarnation of similar effective mechanisms used in the past.

VGCM66

Very interesting observations:

from http://fucampagne2008.unblog.fr/file...lprocedure.pdf

GerardC

Originally posted by OK465 :
Do you mean you have first hand experience of (hand-)flying a 330 in ALT law2 at 35 000 feet ?

Clandestino

Sir, I am just an ordinary airline pilot and flying regional turboprop at that. I am not a psychologist, psychiatrist nor psychoanalyst so I really can not comprehend how can some PPRuNers, which I shall not name, suggest that technique that has been proven lethal for too many an aircrew could be used as an safer substitute for procedures we have now. I just can't get it. It is like someone suggesting potassium cyanide as a panacea for life's ills. Irresponsible at the very least.

One of the first thing a pilot who wants to learn how to fly an aircraft by reference to instruments alone must learn is to stop believing his senses and put his trust in instruments, lest he develops some illusion of attitude, turning or acceleration and kills himself flying. Only when this is lesson is mastered, one can progress on the next level: learning how the instruments can betray him and how to cope with it.

It can be done in many ways but many of them are plain wrong and some are plainly lethal. Proper way to rapidly exit a dive is to use maximum wings level pull that won't either stall or overstress the aeroplane. Pilots whose day at work involves pulling the extreme performance single-seaters out of dive, usually do it more precisely by referring to their alpha and G meters then by feel. Those who fly FBW aeroplanes can even do what Airbus pilots do when escaping windshear or terrain in normal law: pull the stick aft as it goes and let the electrons wring out the maximum performance out of the wings.



While the world outside is dangerous, it is not completely chaotic or anarchic. Industry does make up its mind about safety vs. costs and does it at almost daily basis. What we have here&now is the result of that compromise.

Since you have mention Spanair, configuration indicator in cockpit was working and showing just the wrong config for takeoff. Somehow Mk1 eyeballs, or rather central processing units behind them have seen what wasn't there. If the crew was in such a rush that they didn't read their instruments properly, what were the chances they would pause and use CCTV cameras to check the aeroplane from the outside?

AlphaZuluRomeo

@ Mad (Flt) Scientist & A33Zab:

Thanks for your answers.
Then, the MFPs on Airbus (A380) aren't the same thing I had in mind (re: The Rafale fighter probes).
On the latter, the whole probe (and not only the small "wing" at its external end) moves relatively to the air flow (AoA measurment). As the pitot is at the end of the probe, it too moves and it "always" pointing in the air flow direction. I think it's more accurate for IAS. Does anyone know if that sort of probes exist on any civilian aircraft? Is it only for high performances (fighters/aerobatics) planes?
That's maybe a bit too far off-topic at first glance, but in AF447's scenario, such probes would have maintained the speed above the 60kt limit, and stall warning would not have been inhibited.
Nevertheless, mods if you think it's better to discuss that specific point elsewhere, let me know and I will open another topic

rudderrudderrat

Hi Clandestino,

Do you not use your sensation of deceleration to adjust the amount of braking to be applied, or the sensation of delta g when changing pitch attitude to make it comfortable?

I think you may be confusing spatial disorientation with sensed accelerations.

HarryMann

I suppose that depends on where the screens are, and whether real eyes prefer heads up or head down (psychologically speaking)... that is, a CCTV screen may present itself more in the heads up realm.
Is it not natural to (want to) have a look around the aircraft c.f. focus short in the cockpit on multiply diverse knobs, dials and intsruments...

Indeed, wasn't tghis just one feature of the trim-wheel.. not looked at, let alone noticed and responded too

You cannot keep ignoring the obvious.. there is something wrong with cockpit, systems and instruments, in a human interface fashion, when such obvious things as you say, are ignored, overlooked or found difficult... by all 3 crew (even in a crisis, indeed especially in a crisis which should have got that beady eye scan going quicktime!)

Clandestino

I absolutely do not, sir. For braking I use speed trend arrow, energy caret and ND groundspeed readout (GPS based) against outside visual reference to distance remaining to the exit I'm going after or the end of the runway. For pitch attitude rate I use that nice, big AH display on PFD in front of me. Sir, you heavily overestimate precision and usability of human senses of acceleration and balance in aviation.

The second one, if not corrected by visual references to instruments or outside world, inevitably leads to first one. It's a basic human limitation no eugenics crossbreeding programe will ever be able to eradicate.

And obscure part of instrument panel or outside view?

Position of the trim wheel is completely moot point. Crew needed not be aware of trim position at all. If they pushed forward on the stick, trim would obligingly go towards nose down. Pilot pulled. And stalled. Kept pulling till the vertical distance between his aeroplane and Atlantic ocean became zero. So died.

If none of alleged 32 losses of all IAS indications in high level icing conditions on 330/340s before AF447 ended in PPRuNeable incident (that is, incident discussed on PPRune), then your point of systemic error certainly can not be completely valid. Yes, there was problem with sensors. Yes, airlines and manufacturers were doing something to solve it but they were not in a great hurry, after all, there were 32 crews that coped with the problem successfully. Now we have one that did not and it is absolute imperative (categorical, if you speak Kant) to find out why. It is "the Comet mystery" of our day and age.

And yet there are many PPRuNers working overtime to prove this notion of yours wrong. I try not to ignore obvious but I do strive to ignore the oblivious.

What I find obvious from reactions on the PPRuNE is that the investigation of AF447 reminded some of the inconvenient fact that whenever they fly on the plane what keeps them alive is the knowledge and skills of the guys/gals up front.

OK465

Of course not.

But I have experience that takes the observations out of the realm of pure opinion. (You're welcome to discount anything I say, that's fair, no problem.)

But I would not make general sweeping relativistic statements like:

"Airbus pilots say the A330 is "difficult" to hand fly at altitude."

It's a big swept wing jet that "handles" and accepts proper pilot inputs like any other big swept wing jet in comparable situations, regardless of the active law. Not a "balanced on a pin" new concept out of Area 51.

HarryMann

In theory, yes. In practice, it is marked up for a reason, and this is not the first time time that a quick reference to it, when things aren't going according to plan, would explain all. How they got in that situation is another matter...

Mimpe

Sensed accelleration such as described by the pilot flying in AF 447, would have been a worse than useless perception.

The aircraft was nose up and the pressure being sensed in the back by PF was misinterpreted as possible overspeed...somatogravic disorientation.
The false sensation was then mistakenly responded to with persistent pitch up commands. The pilot seemed anxious and reverting to sensory habit rather than his training.

This aircraft was being hand flown without reference to the pitch aspect of the artificial horizon, and without reference to the altimeter or VSI in the phase leading up to stall.

No sense perception other than what he could see on his primary scan indications was of any use at all....



ps. I am also quite fond of the Categorical Imperative... when in doubt, duty alone will often rescue the day.

Linktrained

The crew of AF447 cannot have seen the latest Stall recovery advice from earlier this year (2011).

PF was/ had been a glider pilot, who must have had many winch launches, when the cable would have been attached under his seat. On releasing from a winch launch the glider would have been nose up, to get the maximum height from that launch and would have required the elevators to put the nose down to retain flying speed.

Someone reduced the thrust to Flight Idle for a few seconds on AF447 and the pitch dropped slightly but the SS stayed towards NU. Then TOGA was reselected.The stall was not recognised.

Would an old fashioned Rate of Climb instrument have helped them to realise that they were going DOWN... before the "passing 10,000 Feet..." on the CVR... The needle's change of direction might be clearer than a tape type display whizzing up/ down, too rapidly to be read. (Think what it might have looked like in Inches !)

Some of the French aircraft that I flew had metric instruments. We just flew the appropriate numbers.

Mimpe

Link....i have no doubt that moving dials trigger the brain better than moving numbers. The primitive visual reflexes for danger in the brain respond less acutely to numerate symbols than dial movement...there's plenty of research on that.

Its a safety issue in extremis, and i feel back up instruments should be live and analogue for that reason.